亚热带常绿阔叶林林下不同生活型植物叶片生态化学计量特征

Leaf Ecological Stoichiometry in Understory Plants with Different Life Forms in a Subtropical Evergreen Broad-leaved Forest

摘要:

为了探究林下植物多样性的形成和维持机制，该研究采用常规和系统发育比较方法对广西猫儿山亚热带常绿阔叶林林下乔木幼树、灌木、草本和藤本等不同生活型植物叶片生态化学计量特征及其与系统发育的关系进行研究。结果表明，叶片化学计量特征的系统发育信号(Blomberg’s K)值为0.020~0.183。叶片N、P含量以及C/P、P/Ca、K/Ca的系统发育信号显著，表明物种多样化过程中存在系统发育保守性。叶片C、N、K和Mg含量以及大多数计量比受到生活型的显著影响，藤本植物有最高的叶片N、K和Mg含量，而草本植物叶片C、Mg含量、C/N和C/P最低。这表明不同生活型植物在总体上对叶片营养元素含量的需求和比例存在差异。进化模型拟合分析表明，对不同生活型最优叶片生态化学计量特征值的稳定选择是最优的进化模型，这表明不同生活型植物在进化过程中选择了适应自身的最优叶片化学计量特征组合。此外，在进化过程中叶片化学计量特征之间存在密切的相关性。因此，物种多样化过程中存在的叶片生态化学计量特征系统发育保守性和最优化稳定选择共同推动了亚热带常绿阔叶林林下植物多样性的形成和维持。

Abstract:

To explore the formation and maintenance mechanisms of the understory plant diversity, the ecological stoichiometric characteristics of leaves of understory trees, shrubs, herbs and vines and their relationship with phylogeny were studied by conventional and phylogenetic comparison methods in Maoershan subtropical evergreen broad-leaved forest, Guangxi. The results showed that the phylogenetic signals (Blomberg’s K) of leaf stoichiometric characteristics ranged from 0.020 to 0.183. The contents of N and P and the phylogenetic signals of C/P, P/Ca and K/Ca in leaves were significant, indicating that phylogenetic conservation existed in the process of species diversification. The contents of C, N, K and Mg in leaves and most of stoichiometric ratios were significantly affected by life form. The contents of N, K and Mg in leaves of vines were the highest, while the contents of C, Mg, C/N and C/P in leaves of herb were the lowest, which indicated that there were differences in the requirement and proportion of nutrient elements in leaves of different life forms. The stable selection of the optimal ecological stoichiometric characteristic values of leaves of different life forms was the optimal evolutionary model, which indicated that plants of different life forms chose the optimal combination of leaf stoichiometric characteristics to adapt to themselves in the evolutionary process. In addition, there was a close correlation between the stoichiometric characteristics of leaves during evolution. Therefore, phylogenetic conservation of leaf ecological stoichiometric characteristics and optimal stable selection in the process of species diversification jointly promoted the formation and maintenance of understory plant diversity in subtropical evergreen broad-leaved forests.